Hybrid reinforcement of 1-dimensional and 2-dimensional carbon nanofillers for improving the efficiency of alumina membranes

Abstract

Members of graphene family, such as carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) have gained great fame in the field of water filtration owing to their extraordinary adsorption characteristics and tradable physicochemical features. Present work focusses on improving the filtration efficiency of plasma sprayed Al2O3 membrane by hybrid reinforcement of CNTs and GNPs in the matrix. A 50 ppm methylene blue (MB) solution was used as the contaminated feedwater. For monolithic Al2O3 coating, porosity and pore size reported were 35% and 1.2 µm, respectively which decreased to 22% and 0.28 µm for the hybrid reinforced coating. Although the reinforced coatings resulted in decrease in the permeability from 452 Lm−2h−1bar−1 (for Al2O3 membrane) to 362 Lm−2h−1bar−1, it yielded the highest rejection rate, ∼98.5%, of MB dye particles from the wastewater and ameliorated the anti-fouling behavior with a flux recovery of 97.3% after the fifth filtration cycle. The improvements in the properties are attributed mainly to the decrease in the pore size and porosity of the coating, formation of nanopores in the graphitic structure, high adsorption properties of CNTs and GNPs. This work might start a new era for the application of hybrid reinforcement in membrane field for high quality filter yield.